Asbestos in asphalt pavements

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In the past, asbestos was used as an aggregate in road surfaces . After the hazard potential became known, the use of asbestos minerals was gradually restricted in each country from the end of the 1970s and later generally prohibited. Today, work safety measures must be taken during road construction work in order to protect those working in the immediate vicinity from the effects of respirable asbestos fibers .

Introduction to the problem

Amphibole asbestos (actinolite) on a nuclear pore filter
Amphibole asbestos (amosite)
Asbestos fibers (chrysotile) in bitumen
Cross-section through an asphalt drill core, image width approx. 5 cm

As early as the 1970s, the public became aware of the problem of the release of asbestos fibers from asphalt road surfaces. The asphalt pavement consists of a mixture of the binding agent bitumen and gravel from natural stones . Basic igneous rocks such as basalt , diabase or gabbro are often used , particularly for the highly stressed surface layer .

These rocks can contain natural components of asbestos minerals from the amphibole family such as actinolite , tremolite , anthophyllite or amosite ( grunerite ). In the past, chrysotile asbestos (white asbestos) was occasionally added to asphalt for particularly stressed road sections such as intersections. The types of asbestos detected in the road surfaces are usually characterized by a stalky to prismatic formation of the asbestos minerals. In the event of mechanical stress (e.g. milling), splinter and fibrous particles can be released which, according to the WHO criteria: L> 5 µm, D <3 µm, L: D> 3: 1 as alveolar (lung) common fibers are rated.

When cold milling traffic areas, reprocessing ( recycling ) the asphalt and reusing it in road construction, 15,000 to 150,000 asbestos fibers per cubic meter of air can be released through mechanical stress and pose a health risk to workers, residents and road users.

Due to the harmful effects of asbestos fibers , the use of asbestos in Germany has been gradually restricted since 1979, until a general ban on the production and marketing of asbestos came into force in accordance with the Chemicals Prohibition Ordinance in 1993 . In Switzerland , a general ban on the use of asbestos materials came into force in 1989, and the EU issued a total ban in 1999, which came into force in 2005.

Legal provisions

In Germany, the Technical Rule for Hazardous Substances ( TRGS ) 517 regulates all activities with potentially asbestos-containing mineral raw materials and preparations and products made from them. There it says:

  • Asbestos fibers are those fibers that, according to their composition, can be assigned to the 6 asbestos minerals. It is irrelevant whether an asbestos fiber was released from a fibrous or non-fibrous deposit of an asbestos mineral .

According to Appendix 1 to TRGS 517, the following types of rock are to be considered as potentially containing asbestos :

The TRGS 517 lists all rocks whose extraction, processing, reprocessing, further processing and recycling of mineral raw materials from the geological framework conditions does not result in the occurrence of asbestos of more than 0.1 percent, so that the production and use ban according to § 18 i. V. m. Annex IV No. 1 Paragraph 2 No. 3 GefStoffV is not affected.

However, it is stated that even if the mass content of asbestos falls below 0.1 percent, exposure to asbestos fibers can occur which requires the legally prescribed protective measures. In investigations of the grit fractions of asphalt, it was found that especially in gabbros and norites, WHO fiber concentrations> 0.1%, total fiber concentrations up to 0.5% and total asbestos contents (fibrous and non-fibrous particles) in the range of several Percentage points can occur.

In Austria , too , the laws prohibiting the use of asbestos and the resulting occupational health and safety regulations were gradually implemented from 1990 onwards. Directive 83/477 / EEC of the European Council of September 19, 1983 on the protection of employees against risks from asbestos at work, last amended in 2003, was implemented in 2006 in national Austrian law. In Switzerland on 1 March 1989, a comprehensive asbestos ban came into force.

Implementation in practice

This article or paragraph presents the situation in Germany . Help us to describe the situation in other countries.

Determination of asbestos content in chippings

In chippings from rocks that are classified as potentially containing asbestos, the content of respirable asbestos (WHO) fibers must be determined using a standardized procedure from the Institute for Occupational Safety and Health of the German Social Accident Insurance (BIA procedure 7487) before use, further processing or recycling .

For this purpose, drill cores from existing asphalt samples are broken up and homogenized, the bitumen and tar content extracted by annealing or dissolving . The material is then ground to a particle size of <100 µm and a portion of the sample powder is suspended in distilled water . The water is filtered and the loaded filter is examined using a scanning electron microscope / X-ray microanalytical method . With a high detection sensitivity of 0.008% by weight, low asbestos contents can be determined. If the (WHO) asbestos fiber concentration is> 0.008% by weight, appropriate protective measures must be taken when handling the material. If the total asbestos concentration is> 0.1% by weight, the GefStoffV prohibits use and the material must be disposed of separately as waste containing asbestos.

Consequences for work in road construction

Large amounts of asbestos fibers can be released, especially when milling asphalt pavements. The legislature stipulates that suitable measures must be taken to effectively protect construction site workers and the population from exposure. Such measures include: a. the blocking of the immediate milling area, combined with a ban on entry for passers-by and construction site workers who do not wear suitable protective clothing, execution of the milling work, exclusively using the wet milling process with water or foam and, in principle, a final wet cleaning. In built-up areas, the population must also be informed in advance of the work. In road construction, the concrete implementation of TRGS 517 and BIA 7487 is handled differently. At the moment only in Lower Saxony (partly also in Hamburg and Schleswig-Holstein) tests for asbestos according to these rules. In other federal states (for example in North Rhine-Westphalia), it is generally assumed that asbestos can be contained in asphalt and, for example, protective measures are taken when milling traffic areas (suction, hot, wet milling). Most federal states do not have any information on the handling of TRGS 517 in road construction.

literature

  • Werner Schnabel: Problems with the removal of fibrous building materials . Roads and civil engineering 44 No. 12, 1990, ISSN  0039-2197 , pp. 27-29
  • Dispose of asbestos dust according to regulations . Roads and civil engineering, 45 No. 5, 1991, ISSN  0039-2197 , p. 51.
  • K. Kolmsee, M. Mattenklott, M. Götz, U. Spod: Asbestos in mineral raw materials. Part 1: Legal situation: application of TRGS 517 and exposure situation. In: Hazardous substances - keeping air clean. 70 (2010) No. 1/2, pp. 37-42. - download as a PDF file
  • K. Kolmsee, M. Mattenklott, M. Götz, U. Spod: Asbestos in mineral raw materials. Part 2: Protective measures according to TRGS 517. In: Hazardous substances - Keeping air clean. 70 (2010) No. 4, pp. 155-158. download as PDF file
  • S. Pierdzig: Asbestos in road surfaces. In: GIT Labor-Fachzeitschrift. 11/2012, pp. 784–786 download as PDF file
  • Federal Institute for Building, Urban and Spatial Research: Dangerous Substance Asbestos , BBSR reports KOMPAKT 2/2010 download as PDF file

Individual evidence

  1. ^ Der Spiegel: Deadly Dust, August 14, 1978 , accessed February 25, 2014
  2. ↑ Arbeitsschutz NRW 2007: pp. 15–16 , accessed on February 25, 2014
  3. ↑ DGUV: BK-Report 1/2013 , accessed on February 25, 2014
  4. ↑ Wolfgang E. Höper: Asbestos in the modern age: industrial production, processing, prohibition, substitution and disposal , Cottbus studies on the history of technology, work and the environment, Volume 32, Waxmann, Münster 2008, ISBN 978-3-8309-7048- 4 , p. 198ff
  5. ↑ Technical rule for hazardous substances 517: Activities with potentially asbestos-containing mineral raw materials and mixtures and products made from them , published in GMBl 2013 p. 382–396 of April 9, 2013
  6. ↑ TRGS 517, Annex 1, p. 30f.
  7. ↑ TRGS 517 No. 1 Paragraph 5, p. 2
  8. ↑ TRGS 517 No. 1 Paragraph 5, p. 2
  9. ↑ Federal Law Gazette II No. 242/2006 : Amendment of the Limit Value Ordinance 2003 and Construction Worker Protection Ordinance
  10. ^ Forum Asbestos Switzerland: Asbestos ban , accessed on February 25, 2014
  11. ↑ In: IFA workbook measurement of hazardous substances. 31. Lfg. X / 03. Ed .: German Social Accident Insurance eV (DGUV), Berlin. Erich Schmidt, Bielefeld 1989 - loose-leaf edition, [1]
  12. ↑ Arbeitsschutzbericht.NRW, p. 16 , accessed on February 25, 2014
  13. ↑ Strassen.NRW: Asbestos: New regulations for asphalt milling , accessed on February 25, 2014
  14. ↑ Stefan Pierdzig: asbestos in road surfaces. GIT laboratory journal. 11/2012, pp. 784–786, November 19, 2012, accessed on March 12, 2018 .